1. Field
The invention relates to automatic target recognition systems. Since experience has shown that such recognition is only a probability these systems are now referred to as Aided Target Recognition system (ATR'S).
2. Prior Art
Prior art ATR systems have been attempted with every type of sensor including both active and passive types. The probability of recognizing a given target is directly proportional to the amount of information (e.g. contrast variations) known about the target, i.e. data supplied by sensors. Active sensors like RADAR, SONAR and LIDAR often provide more useful information than passive sensors such as TV cameras and IR imagers, however, the latter type of sensor is preferred for covert operation, which is often required for tactical military operations and many civilian users.
To maximize the probability of detection of a specific target with an optical or passive type sensor, the threshold parameters required to identify a target must be reduced to a minimum. This in turn increases the likelihood that another target found by that sensor will be mistaken for the specific target, thus increasing the error or false alarm rate. The user is thus placed on the horns of a dilemma in trying to decide whether probability of detection is more important than false alarms. The problem is eased by selecting a smart sensor, i.e., a sensor which has the highest probability of detection for a given false alarm rate. Potentially smarter systems with two sensors exist, but where automatic recognition is employed it has been the policy of system designers to make all decisions only with the smartest sensor. Thus the Forward Looking Infrared Imager (FLIR); a smart sensor as opposed to a TV camera or an image intensifier, which are easily confused by shadows and camouflage; has emerged as the decision maker in most passive systems.